Motor vehicle and braking system therefor



Dec. 15, 1936. M. ROCKWELL 2,054,533

MOTOR VEHICLE AND BRAKING SYSTEM THEREFOR Original Filed Sept. 10, 1927 5 Sheets-Sheet 1 Dec, 15, 1936. v H. M. ROCKWELL r 2,064,688

MOTOR VEHICLE AND BRAKING SYSTEM THEREFOR Original Filed Sept. 10, 1927 5 Sheets-Sheet 2 20 I i 1 5% z/ A i i 4/ I 3 J 5 7 AT 0 NE) Dec. 15, 1936. H. M. ROCKWELL MOTOR VEHICLE AND BRAKING SYSTEM THEREFOR Original Filed Sept. 10, 1927 5 Sheets-Sheet 3 E0 25 (Eh l(/ /ffy m v 20 Dec. 15, 1936. f H. ROCKWELL 2,064,688

' I MOTOR VEEICLE AND BRAKING SYSTEM THEREFOR Originai Filed Sept. 10, 1927 5 Sheets -Sheet 4 11v VENTOR.

; TOE) Dec. 15, 1936. H. M. ROCKWELL MOTOR VEHICLE AND BRAKING SYSTEM THEREFOR Original Filed Sept. 10, 1927 -5Sheets-Sheet 5 Fatented Dec. 115, i936 entree s PATENT FWQE MQTOR VEHIICLE AND ERAKENG SYSTEIW THEREFOR Hugh M. Rockwell, Frecport, N. I.

16 Glaims.

This invention relates generally to motor vehicles and the like, and has particular reference to improved fluid pressure brakes and braking systems for vehicles.

Among the important objects of the invention, in its broader aspects, are: to provide a hydraulic braking system for vehicles wherein oil is used as the pressure medium and wherein the master cylinder is supplied with oil from the engine oiling system; to provide a novel master cylinder of simplified construction for hydraulic braking systems; to provide a hydraulic brake system which will be self-venting and entirely free from air pockets; to provide such a brake system wherein the pressure-fluid conduits will be well protected from injury; to provide hydraulic brakes of simplified form applicable to the steerable wheels of a vehicle and capable of transmitting equalized pressure to the several brake 20 drums; to provide fluid-pressure brakes with simplified means for applying power to the brake bands; to provide fluid-pressure brakes which will be self-energizing and wherein novel floating connections are disposed between the brake cylinders and the brake bands.

Prior to this invention, a number of hydraulic brake systems for motor vehicles have been proposed and some of them have gone into commercial use, but they have all employed certain defects which have given rise to serious objections. In some instances, the proposed constructions have been too complicated, and therefore, too costly to produce for automobile use, while in others, mechanical defects and limitations have detracted from their utility. One of the principal defects found in most hydraulic braking systems lies in the formation of air pockets, due to the fact that the master cylinders and the wheel cylinders are at substantially the same level, and when air becomes trapped in the system, it results in lost motion. Such systems have made use of a special oil which is comparatively expensive and which, from time to time, requires replenishing in order to compensate for leakage in the system. Another objection has arisen from the arrangement of the fluid conduits, which in themselves have been expensive, because of requiring numerous frame fittings and the like, whereby to be properly supported, and in all such devices which have gone into commercial use, such conduits have been exposed throughout portions of their length, particularly adjacent the wheels, and have thus been subject to accidental injury. This is particularly true in connection with brakes applied to the front wheels of automobiles, since in such applications the conduits supplying the fluid to the wheel cylinders must necessarily be flexible and provided with considerable slack in order to permit the turning of the wheel for steering the machine. V

The foregoing and other defects of the prior art are overcome by the present invention, which more specifically contemplates'the provision of fluid-pressure brake systems for automobiles and the like, the new construction being extremely simple, eificient in use and economical in production. To achieve these results, the wheel cylinders are located at pointsv below .the axes of the wheels and the master cylinder is located at a substantial distance above said axes and the fluid conduits are gradually inclined downwardly'from the master cylinder to the various wheel cylinders. The master cylinder is preferably of an improved and simplified form, having the pedal mounted directly upon the upper end of the plunger rod, which is operable for creating the braking pressure in the system, and said master cylinder has been shown in the drawings as being sup-plied with oil from the crankcase of the engine of the vehicle. The lubricating oil from the engine is, of course, under pressure, and for this reason it is possible to circulate the oil through the master cylinder. One of the principal features in this connection is that the oil is returned from the master cylinder to the crankcase at the highest point in the system. Naturally, any air leaking into the conduits or other part of the system will tend to rise, and, working up to the upper end of the cylinder, it will also pass along into the engine crankcase. The oil is conducted from the master cylinder in a longitudinal conduit, which extends forwardly or rearwardly, as the case may be, to the axle of the vehicle, and from there a pair of lateral branches extend to the wheel cylinders and are preferably carriedby the axle. In the illustrated embodiment, said lateral branches extend inside of the axle, whereby to be entirely covered and protected, and this feature is par-' ticularly desirable where the cylinder is located below the axle, since in such a construction it is 5 necessary that the axle be free from encumbrances which would interfere with jacking up the same in making tire repairs, etc. In the case of the front wheel brake, the Wheel cylinder is mounted in the king pin, about which the steer- 50 ing knuckle turns, and due to this coaxial arrangement, the oil can easily be conducted to the cylinders. A novel floating connection is pro-- vided between the wheel cylinder piston and the corresponding brake band, the arrangement being such that the wear on the brake band will at all times be uniform throughout its entire periphery. Some of the principal features of this invention have been disclosed in my earlier application for Letters Patent on Stop light switches and brake systems for vehicles, Serial Number 195,107, filed May 28th, 1927, but these features have not been claimed in said earlier application.

The foregoing and other objects, features, and advantages of the invention will be more readily apparent from the following description in connection with the accompanying drawings, wherein the invention has been shown by way of illustration, and wherein Figure 1 is a top plan view of an automobile chassis equipped with a braking system in accordance with this invention;

Fig. 2 is a vertical, longitudinal, sectional view through the same with parts broken away;

Fig. 3 is a fragmentary, vertical, transverse, sectional view through one of the front wheel mountings of the vehicle;

Fig. 4 is a substantially vertical, longitudinal, sectional View on line l l of Fig. 3, and drawn on a larger scale;

Fig. 5 is a. vertical, transverse, sectional view on line 5---5 of Fig. 3, and showing one form of connecting the fluid conduits to a forged axle;

Fig. 6 is a vertical, longitudinal, sectional view through one of the wheel cylinders and part of the corresponding brake drum, and illustrating more clearly the connecting means between the cylinder and brake band when the brake is applied;

Fig. 7 is a fraginentai", sectional view on the line "IL-J of Fig. 6;

Fig. 8 is a detail, perspective View of one of the floating levers disposed between the wheel piston and one end of the brake band;

Fig. 9 is a substantially horizontal, detail, sectiona-l View on line 99 of Fig. 3 and showing the key-washer for the king pin;

Fig. 10 is a fragmentary, sectional view through a tubular front axle and showing the means for conducting the fluid therethrough;

Fig. 11 is a fragmentary view, partly in elevation and partly in vertical section of the rear axle of the vehicle of Fig. 1;

Fig. 12 is a top plan view thereof with parts broken away and parts in section;

Fig. 13 is a horizontal, transverse, sectional view on line l3i3 of Fig. 11, and drawn on a larger scale;

Fig. 14 is a vertical, transverse, sectional view on line M-Hl of Fig. 11 on a larger scale;

Fig. 15 is a similar sectional view on line lfi-l 5 of Fig. 11;

Fig. 16 is a vertical, longitudinal, sectional view through one form of the improved master cylinder and showing the plunger in its normal position of rest;

Fig. 17 is a transverse, sectional view on line iL-l'i of Fig. 16;

Fig. 18 is a transverse, sectional view on line i8-I8 of Fig. 16;

Fig. 19 is a transverse, sectional view on line 29-59 of Fig. 16, and drawn on a larger scale;

Fig. 20 is a vertical transverse sectional view on line 28-28 of Fig. 16 and showing one method of connecting a signal light switch to the master cylinder;

Fig. 21 is a vertical, longitudinal, sectional view through an automatically adjustable abutment used in connection with a self-energizing brake band, as shown in Fig. 4, and

Fig. 2 2 is a vertical, transverse, sectional View through an automatically adjustable support for said self-energizing brake band.

Referring to the drawings in detail, the invention has been shown as applied to a motor vehicle which comprises a chassis frame A resiliently supported by front and rear springs 2 and 3, respectively connected to front and rear axles 4 and 5. The front axle 4 is equipped with the usual steerable road wheels 6 and the rear axle is equipped with the usual traction wheels l, and power is supplied to said rear wheels 1 from a motor 8 through a propeller shaft 9 in connection with the internal mechanism of the rear axle 5. The front wheels 6 are rotatable on spindles Hi, (Fig. 3), which extends outwardly from steering knuckles I I, said steering knuckles being movable about the axes of the king pin 12 in the yoke ends of the front axle 4, and the steering being accomplished by links i3 and I4 operable by a steering gear I 5 in the usual well known manner. The motor vehicle illustrated in the drawings is equipped with a four-wheel brake system, in which the front and rear wheels are respectively provided with brakes i6 and H, which are operated by a suitable fluid under pressure, supplied from a master cylinder [8. The fluid employed is preferably oil, and the master cylinder is mounted in a fixed position above the axles, while the brake cylinders are located below the axles and the arrangement is such that the entire system will be self-venting and substantially free from air pockets. The front and rear brakes iii and H are essentially the same in details of construction and in principles of operation, there being slight differences due to the fact that the front wheels must necessarily be moved about the axles of the king pin, whereas the rear wheels have no such movement. However, it is thought that a detailed description of only one of these brakes will be sufficient for a complete understanding of the invention, and by reference to Figs. 3, 4, 6, 7 and 8, a complete description of one of the front wheel brakes IE will be given.

Each front wheel brake It includes a hollow brake drum 29 secured as by rivets or bolts 2! to the wheel 6, and within the drum 20 is an expansible brake band 22 having on its outer surface a suitable facing or lining of friction materail 23 for engagement against the inner periphery of the cylindrical flange portion 24 of the brake drum 29. The brake band 22 is preferably in the form of a split band or ring of cast iron, spring steel, or other suitable material tending to retract by virtue of its inherent resiliency, and each of its ends is suitably reinforced by hardened steel blocks 25 secured in any desired manner. The proportions of the parts are such that the opposed reinforced ends 28 and 29 of the brake band 22 are spaced apart, as best shown in Fig. 4, and are respectively engaged by the heel portions 30 and 3| of actuating levers 3'2 and 33, which are pivoted at 34 and 35 to the free ends of links 35 and 37, said links in turn being pivotally supported on fixed pins 38 and 39 extending inwardly from a stationary mounting and dust plate 40. The plate 49 is circular in outline, to correspond with the brake drum 2! and has a central indented portion 4| secured to lateral flanges 42 of the steering knuckles H, whereby to be held firmly in stationary position. The brake band is maintained in a floating, selfenergizing condition by means of an abutment 43 which is secured to the inner surface of the plate 40 in such manner that one or the other of the ends 28 and 25 of band 22 will abut against the same, dependent upon the direction of rotation of the brake drum. With this arrangement, as the brake is applied the accumulated torque is made use of to assist the braking action. Necessarily, there will be slight relative rotary movement of the brake band in the two reverse directions of rotation of the brake drum, and the suspension of the levers 32 and 33 on the links 36 and 3'! afford compensation for this slight shifting movement. The brake band 22 is supported in a substantially central position with reference to the brake drum by means of supporting members 44 which are carried by the plate til and spaced equi-distantly around the edge thereof. Said supporting members 44 and abutment 53 preferably include automatic adjusting means for taking up the slack in the brake band in order to compensate for wear in the band, and these automatic adjusting means will be more fully described hereinafter.

The brake actuating levers 32 and 33 are sub stantially alike in structure but disposed in opposition to each other, as best shown in Figs. 4 and 6. Said levers respectively include toe portions 45 and it, which are wider than the heel portions til and 34, and the outer surfaces of which are machined or otherwise formed in true arcs struck from the centers 3 and t respectively, or as cams if desired. Said arcuate toe portions 15 and it are constantly in rolling contact with each other, they being maintained in such condition by virtue of the inward pressure of the ends of the brake band against the heel portions of the levers. Because of this arrangement, said levers 32 and 33, together with their corresponding links 36 and 31 are maintained in a floating condition between the ends of the brake band and thus are capable of slight shifting movement with reference to the vertical center of the brake drum, the direction of such shifting being controlled by the direction of rotation of the brake drum. The toe portions 45 and d6 of these levers are situated at greater distances from the centers i l and 35 than are the heel portions 38 and 3!, the result being to provide asubstantial leverage whereby the brake band can be expanded with less eifort on the part of the operator. It will be noted that the heel portions 3t and it! have a free sliding or a combined sliding and rolling contact with the ends of the brake band and that the toe portions 45 and 46 have a similar contact and/or engagement with the piston 58. As best shown in Fig.7, the links 3t and 3! are preferably disposed in spaced parallel pairs with the corresponding levers arranged between them, and the lower ends of said links are apertured for the reception of pivotal pins Bid and 35a, carried by the levers. The outer or upper ends of the lever toe portions t5 and terminate close together, as best shown in Fig. 6, and bear against the bottom surface 6? of a piston 48, which is mounted for reciprocation within a cylinder The piston i8 preferably includes a skirt portion 59 which depends below the surface it in such manner as to provide a socket for the reception and retention of the lever toe portions, and said piston is preferably formed of steel or similar suitable material accurately machined with a smooth exterior to fit within the smooth bore of the cylinder t9. Said cylinder la has no closure at its lower end other than the piston, and this general construction is extremely simple as compared with prior art devices wherein the piston has been completely enclosed within the cylinder, fitted with a piston rod and various types of packing rings, etc. It will also be noticed from Figs. 3 and a that said cylinder 49 is disposed a substantial distance below the axis of the wheel spindle iii and coaxial with the king pin 52, and this arrangement is important in that it provides a substantial difference in level between the wheel cylinder and the master cylinder, whereby to prevent the formation of air-pockets, and further, because it renders the connection of the oil conduits to the cylinder much simpler. In the preferred embodiment of the invention, the cylinder 519 is integral with the king pin 52 and forms in effect an enlarged head for the lower end thereof, said'head being joined to the body of the king pin by a tapered shoulder portion 5! which is adapted to seat in a countersunk hole 52 in the lower axle yoke end id. At its upper end the king pin i2 is provided with a keyway 53 for locking engagement with a lug 54 of a keywasher E55, (Fig. 9) said keywasher 55 being disposed within a recess on the upper side of the axle yoke end 11) and firmly held against rotation with reference thereto. Overlying the keywasher 55 is a thrust washer 55 and lockwasher M, by means of which a looking screw 58 is maintained in fixed position in the end of the king pin.

Extending inwardly from the tapered shoulder iii of the head of the king pin is a hole to which forms communication with the bottom of the cylinder d9, as best shown in Fig. 3, and at its outer end said hole Ed is in communication with a bore ti extending upwardly at a gradual inclination from the yoke end lat to the body of the axle 4. Said bore 6! forms a laterally-extending oil conduit from a point in the axle intermediate the ends thereof and completely eliminates the flexible tubing which has been necessary in connection with prior art hydraulic or other fluid-pressure brakes. The elimination of such tubing considerabiy reduces. the cost of manufacture of the complete system, since such tubing has been expensive and at the same time it provides an oil conduit which is entirely concealed, and therefore, protected from injury. In Figs. 3 and 5, the invention has been shown in conjunction with a forged axle of well known form, having an I-beam cross-section and wherein said inclined bore ti extends through the web portion 62 of the axle. There are, of course, two bores Bl extending in opposite directions and converging at a point adjacent the upper side of the axle where they both intersect a rearwardly extending bore 53. The bore @333 is at the bottom of an enlarged boss M which is counterbored for the reception of a ring or ferrule t5 tightly fitted upon the extremity of a flexible tube 6%, and said boss ti l is exteriorly screw-threaded, whereby to receive a tube-clamping nut Bl which firmly holds the extremity of the tube 66 in position on the axle. The tube 5% may be of any ordinary or preferred form, preferably having an inner flexible metallic lining covered by vulcanized fabric or the like, such tubing being specially designed to withstand the destructive effect of oil on rubber. The ring t5 is preferably formed of some malleable metal having its interior surface suitably roughened as by fine screw threads or the like, whereby it may firmly engage the exterior of the extremity of the tube '56 in such a manner as to have a permanent mechanical union therewith. As best shown in Fig. 2, the tube 66 extends gradually upwardly and rearwardly, and has its other end connected to the lower end of the master cylinder 48, and

said tube 66 is provided with sufiicient slack to compensate for relative movement between the frame l and the axles of the vehicle.

From the foregoing it will be seen that when the braking system is filled with oil or some other fluid, increase of pressure originating in the master cylinder will be transmitted through the tube 68 and the conduits 6i and 69, respectively, to the cylinders 49, causing the pistons 48 to be moved outwardly, and moving with them the levers 32 and 33 in such a manner as to swing the same about their respective pivots 34 and 35. Such movement tends to increase the distance between the respective heel portions 38 and 3|, and thus expands the brake bands 22. As pressure in a fluid is transmitted equally in all directions, it will be evident that the braking force on the several brakes is equalized, and as the pressure is relieved, the pistons 48 will return to their original positions, followed by the toe portions 65 and =16 of the actuating levers. The pressure is generated in the master cylinder through the instrumentality of a foot pedal or manual control, and while any one of a number of well known forms of. master cylinders may be employed in conjunction with the improved brakes above-described, I prefer to use a master cylinder of simplified form similar to that disclosed in the drawings, and such improved master cylinder will be described presently.

As best shown in Figs. 16 to 20 inclusive, the master cylinder 53 comprises a tubular body 69 which may preferably be formed as a casting and is mounted in an inclined position adjacent to and preferably below the floor board 18 of. the vehicle. At its lower end, the cylinder I8 is screw-threaded, as at H, for the reception of a nut l2 which firmly clamps in place the rear end of the oil tube 66, said rear end of the tube having a ferrule "l3 similar in all respects to the ferrule 65 already described in connection with Fig. 5. Intermediate of its ends, the cylinder body 69 has a smooth bore preferably reamed as at M and this reamed portion constitutes a sealing chamber within which a plunger I is adapted to reciprocate to generate pressure in the fluid. To facilitate manufacture, the internal diameter of the body 69 is enlarged, both above and below the reamed portion 14, and suitably related to the stroke of the plunger 15, said upper enlarged portion '56 is provided with a plurality of spaced lugs Tl which constitute guide means for the lower end of the plunger 15 when it is in its normal retracted position. The plunger 15 is preferably in the form of a smooth cylindrical rod adapted to fit snugly in the reamed portion 14 of. the cylinder body and preferably has. its upper extremity slightly reduced in diameter to provide a plunger rod '58 which extends outwardly from the master cylinder and through a packing gland l9. Suitable packing 88 is confined within said gland l9 by means of a metallic gland washer 8| so as to effectively prevent leakage of oil from the master cylinder outwardly through the gland. By particular reference to Fig. 2, it will be noticed that the gland i9 is at the highest point of the entire braking system, and therefore, the oil level is lower than said gland. This arrangement is particularly important in that it reduces leakage of oil to a minimum. A foot pedal 82 is mounted upon the upper end of the plunger rod 18 by means of a stud 89, or other suitable means, and said pedal 82 has been shown as being equipped with the usual pedal pad 84 of. any ordinary or preferred type.

At any suitable point below the reamed portion 14 of the cylinder is an intake port 85 which is in communication with a nipple 86, threaded or otherwise secured to the body portion 69 and which provides at its outer end a screw-threaded connection for a coupling 81 associated with an oil supply pipe 88. The lower end of said oil supply pipe 88 is similarly connected to the crankcase of the engine 8 in such manner as to be supplied with oil from the usual pressure oiling system of the engine. This may be effected in any desired manner as by connecting the pipe 88 to the discharge pipe 11 of the usual lubricating pump 1;. In the illustrated embodiment, the outer end of the nipple 86 is provided with a reduced orifice 89 within which is slidable a pin 90 carried by a valve 90a, which is influenced by a compression spring 9|. Said pin 98 may have a substantially triangular cross-section, as best shown in Fig. 19, whereby to allow passage of a small volume of the fluid through the aperture 89 and past the valve, and the arrangement is such that as the main plunger 15 is operated, the pin 90 will be caused to reciprocate slightly within and beyond the end of the aperture 89 and prevent clogging of the aperture 89. Adjacent the upper end of the reamed portion 14, the cylinder body 69 is provided with an oil return port 93 which is in communication with the longitudinal bore 94 of a plain nipple 95 and the outer end of said nipple 95 is screw-threaded for connection with a coupling 96 similar to the coupling 81 and forming a detachable connection for an oil return pipe 91, the lower end of which is also connected to the engine crankcase to return the oil thereto. When the plunger 15 is in its normal position of rest at the upper end of the stroke, it has passed entirely out of the reamed portion M of the cylinder and has partly uncovered the port 93, leaving the same in communication with said reamed portion 14 and the lower chamber 98. In this condition oil is free to circulate through the master cylinder, it coming in through the tube 88 and returning to the engine lubricating system through the tube 91. Furthermore, any air in the braking system quickly works its way upward to the upper end of the system and passes out through the tube 91 for dissipation in the crankcase. In view of the fact that the orifice 89 in the nipple 86 is so restricted, the normal pressure of the fluid in the master cylinder will be very slight; in fact, sufiicient only to insure a return of the surplus through the tube 91, and since the upper end of the plunger 15 comes to rest at a point above the return port 93, it will be evident that any oil which might adhere to the side of the plunger in its upward stroke will be free to float downwardly in the clearance provided between the side of the plunger 15 and the enlarged counterbored portion 16 of the cylinder body.

Intermediate its ends, and preferably at the lower side thereof, the cylinder body 69 is provided with an angularly disposed threaded boss 99, which is centrally bored as at N to communicate with the oil chamber 98 and adapted to form a connection for a nut l0! carried by the forward end of a flexible tube I02. Said tube I 02 is similar to the tube 66 and extends rearwardly and downwardly to the rear axle 5, to which it is connected by means of a coupling I83, as will hereinafter be explained.

Extending downwardly from the master cylinder body 69, and preferably integral therewith, is a substantially circular body member I04 having a fluid recess I65 in communication with the chamber 98 by means of a downward passage I06, and associated with said circular portion IM is a fluid-actuated switch by means of which a signal lamp may be controlled automatically as braking pressure is generated in and transmitted through the braking system. Such a switch may preferably be of the type and construction disclosed in my above-identified, earlier application bearing Serial Number 195,107. In that application, the switch has been shown as disposed at the extreme lower end of the master cylinder, but, of course, it may be mounted in any other part of the system, as explained in said application, or, if desired, such a fluid-actuated switch may be entirely eliminated or replaced by some other type of switch. Since the arrangement of the switch is not a feature of the present invention, it is thought that a detailed description thereof is unnecessary in the present specification.

In order to mount the master cylinder I8 upon the chassis frame I, any suitable form of bracket may be employed, but I have chosen for illustration a mounting which enables said master cylinder to be adjusted either longitudinally or angularly, or both, as desired. Such an adjustable mounting has been shown in connection with Figs. 16 and 17, and comprises a ball member III! which is adapted to be clamped in a spherical seat I II of a bracket H2. The bracket IIZ may be secured to the dash M3 or other part of the chassis by means of bolts and nuts, as at I I4, and, if desired, the lower end of the bracket may be held against vibration by means of a brace rod I I5 secured to the lower side of the toe board III of the vehicle. The lower end of the bracket, which constitutes a socket for the ball III], may be split, as at I I6, and provided with a clamping screw III by means of which the walls of the socket II I may be caused to tightly grip the ball III], whereby to hold the same in the adjusted angular position. Similarly the ball I It is formed with a kerf or slot H8 which renders said ball sufficiently yieldable to tightly grip the cylinder. A screw-threaded bore H9 extends entirely through the ball member III! and is adapted to receive the cylinder body 69, the upper end of which is exteriorly screw-threaded, as at I20. In order to adjust the device to the desired position, it is merely necessary to unloosen the screw I I1, whereupon the cylinder may be moved longitudinally by virtue of the threaded connections I I9 and I20, or it may be moved angularly about the center of the ball member III). After these adjustments have been made, the clamping screw II'I may be again tightened to hold the parts firmly in their adjusted positions. Such a mounting bracket is particularly desirable in that it makes possible the mounting of the master cylinder upon different types and sizes of vehicles, wherein the relative proportions necessarily vary, and thus a single master cylinder and mounting bracket may be a standardized unit for all commercial vehicles. Such a standardized mounting is not necessary, however, to the successful practise of the invention, and in some installations the master cylinder might be otherwise mounted.

In Figs. 11 to 14, inclusive, the salient features of the invention with reference to the rear axle 5 and rear wheel brakes II have been illustrated. Said rear axle 5 is preferably hollow and comprises the usual differential housing I2I carrying the laterally extending tubes I22, which are provided at their outer ends with the usual spring seats I23. As its name implies, the differential housing I2I encloses the differential gearing which constitutes the driving mechanism from the propeller shaft 9 to the axle drive shaft I24, by means of which the rear wheels I are rotated. Said differential gearing has not been illustrated in the drawings and may be of any of the ordinary well-known types. At any suitable point in its length, and preferably adjacent the differential housing IZI, the rear axle 5 is provided with a forwardly extending boss I25, the outer end of which is screw-threaded, as at I25, for the reception of the coupling III? of the oil conduit I02.

Said boss I25 is provided with a counter-bore I2'I,

within which is seated the ferrule I28 of the coupling ms, and extending inwardly from the bottom of said counter-bore to the interior of the tubular axle are a pair of smaller bores I29 and I 30, both of which are in communication with the interior of the flexible oil conduit I92. Anchored in the bore I29 is one end of a relatively small tube I3I which is disposed more or less helically within the axle tube I22 and extends toward the right rear wheel. Similarly anchored in the bore I353 is a. tube I32 which extends around the inner side of the differential housing plate I33 and bends laterally to the left rear wheel I. The ends of said tubes I35 and I32 are slightly flared, as at Iitd, and held firmly in place by sleeves I35, the respective bores of which are preferably connected together by means of a transversely milled slot I36, (Fig. 13). The tubes ISI and I32 may be formed of copper or other desired material and have their outer ends deflected and extending through openings It'l adjacent the extremities of the axle tubes I22, and said deflected ends of the tubes are firmly anchored, as at I38, in the spring bottom portions of the seat members I 23.

The rear brakes II are substantially the same as the front brakes I6, with the exception that instead of being mounted in or with the king pin I2, the wheel cylinders 49a are formed with angularly disposed attaching portions I39 which are secured by means of bolts I II) to the enlarged portions MI in which the extremities of the tubes I22 are anchored at I38. Each of the rear wheel cylinders Ma is provided with a piston Q8 of the same character as that already described in connection with the front wheel brakes, and fluid is supplied to the cylinder to actuate said piston through a bore M2 which connects the cylinder with the adjacent tube end I38. In this manner the lateral branches of the oil conduits are contained and concealed within the tubular axle and thoroughly protected from injury, and adjacent the rear wheels are no exposed flexible tubes customary in the prior art devices and hence nothing to interfere with jacking up the axle when necessary. The operative connection between the rear wheel cylinders 49a and the brake bands are identical with such connections in the front wheel brakes and the rear brake drums 20a are secured to the rear wheels in the same manner as the front wheel drums 20 are mounted.

Initially, the entire braking system, including the master cylinder I8, the longitudinal conduits 66 and I02 and the lateral conduits 6|, IiiI and I32 are filled with the braking fluid, which, as already explained, is oil. In some instances it might be desirable to have two different fluids in the system, particularly when the vehicle to which it is applied is driven in severely cold weather. Under such use the engine oil will circulate through the master cylinder from and to the engine crankcase, and by virtue of its circulation will be kept sufficiently warm by the heat of the engine to prevent congealing, whereas the fluid in the conduits adjacent the wheel cylinders might congeal sufficiently to cause the brake to be stiff and sluggish in action. To remedy such a condition, the lower part of the braking system may be supplied with a fluid which will not congeal except at a temperature lower than normal and which will not mix with the oil, while the upper part of the system is supplied with the cylinder oil in the manner already described. One fiuid which may be used in the lower part of the system in this way is glycerine, and for still colder temperatures, a mixture of glycerine and alcohol in approximately equal parts will remain in proper condition to transmit braking pressure.

In connection with Figs. 3 and 5, certain features of the invention have been shown in a forged front axle having an I-beam cross-section, but it is to be understood that these features can also be incorporated in a tubular front axle, such as is used by some automobile manufacturers. Such a tubular axle has been illustrated in Fig. 10, in which the king pin I2 extends through the yoke end I45, which is secured as by welding or otherwise to the end of the axle tube M5. The lower arm I41 of the yoke end I45 is provided with an inclined hole I48, which, at its inner end communicates with a similar hole in the wall of the axle tube I46. A lateral branch conduit I45 extends through the axle tube Hi6 and has its lower end anchored in the hole M8, said anchorage being preferably effected by flaring the end of the tube I49 and clamping it between a pair of clamping blocks I50 and lI. The sleeve I5I communicates with the port Gil in the kingpin and with the interior of the tube M9, and there are, of course, two such tubes I59, one extending to each of the side wheels at the front axle and connected in any suitable manner to the longitudinal conduits 65.

As has previously been stated, the abutment member 43 and the supporting members 44 are preferably provided with automatic adjusting means whereby to compensate for wear of the brake band, and such automatic means is shown in Figs. 21 and 22 of the drawings. The abutment 43 comprises a bifurcated base i55 which is preferably integral with the mounting plate 40, and rotatably supported in said base I55 is a spool I56 which is held against longitudinal movement by virtue of end flanges l5 engaging against the ends of the base I55. A longitudinal bore I60 extends through the spool I56 and has one of its ends provided with a right-hand thread i58 and the other end provided with a left-hand thread I 59, said threads extending inwardly from the opposite ends of the spool. In the illustrated embodiment, these threads have been shown as of the buttress type, but obviously, they may be of any other standard form desired. Screw-threaded studs I65 and I6I are respectively mounted in the threaded sockets I58 and I59, and extend outwardly from the opposite ends of the spool I56, said studs being held against rotation by guide fingers I62 engaging in grooves I63 in the inner surface of the plate 4 The threaded portions of the studs lfiii and iIiI have a comparatively loose fit with the respective threads I58 and E59, and a torsion spring I63 forms a connection between the studs I 55 and IGI and the spool I56 in such a manner as to impart a relative rotary motion between these parts. Said spring I64 is anchored intermediate its ends,

as by a pin I 55 and has its opposite ends connected, as at I66, to the respective studs Hill and IGI. Each of the studs I65 and Hit is further provided with a yieldable plunger I6! normally under the influence of a compression spring i533, said plunger being adapted to extend slightly beyond the extremity of the corresponding stud an amount equal to the clearance to be provided for the expansion and contraction of the brake band. Under normal conditions, the engagement of the ends 28 and 29 of the brake band against either the plungers it! or the extremities of the studs E65 and IE5 will impose sumcient friction on the threaded connections between the studs and the spool l56 to prevent rotation. of said spool. When the brake band lining 23 becomes worn sufficiently to permit expansion of the band to the point where the ends 28 and 29 actually move away from the extremities of the plungers IIi'I, the above-mentioned friction will be eliminated, and thereupon the torsion spring ltd is free to rotate the spool I55. Such rotation tends to increase the distance between the ends of the respective spool studs until the slack is taken up and this action will continue automatically throughout the entire life of the brake band lining.

The construction and operation of the automatically adjustable supporting members 44 are somewhat similar to the construction just described in connection with the abutment 33. Each of said supporting members includes a fixed boss ill}, preferably integral with the mounting plate 40 and extending inwardly to the interior of the drum iii, and said boss Ilil is provided with a radially extending bore having a screw thread, which, in the drawings, has been shown as of the buttress type. A plug H2 is anchored at the inner end of said threaded bore Ill and a rotatable stud I'ii disposed in the outer end of said threaded bore and adapted upon rotation to move radially with reference to the brake drum. The plug H2 and stud H3 are respectively provided with counterbores I'M and IE5 for the accommodation of a torsion spring Ht, the lower end of which is anchored to the plug I72, and the upper end of said spring being connected to the stud H3 in such manner as to exert a rotary force tending to move the stud outwardly away from the axis of the brake drum. At its outer end the stud H3 has a reduced concentric extension Ill which is bored and counterbored for the reception of a plunger Iii? and compression spring I19 similar to the plunger I El and spring I 68, described in connection with Fig. 21. The possible movement of the plunger Hi8 beyond the end of the stud extension H7 is equal to the predetermined clearance bctween the brake band lining and the interior of the brake drum flange 54, and while the stud Il3 is normally prevented from rotation by virtue of frictional engagement of its threads with those of the bore IlI such frictional engagement is relieved when the brake band lining wears beyond the predetermined limit, and thereafter the spring W6 will slightly rotate the stud i'lS to compensate for such wear. It is, of course, to be understood that the automatically adjustable supporting members 45 may be used with an anchored brake band of any ordinary or preferred type, in which case the abutment 43 is not required, and furthermore, the adjustable abutment 43 may be used without the adjustable supporting members it. While the automatic adjusting means to compensate for wear of the brake band lining has been illustrated and de scribed herein, they are not claimed in this application, but are made the subject-matter of a separate application for United States Letters Patent bearing the Serial Number 218,657, filed September 10, 1927.

It is thought that the operation of the invention will be thoroughly clear from the foregoing description, but brief recapitulation will be resorted to. Under normal conditions, when the brake is off the brake bands 22 will be contracted and entirely out of engagement with their respective brake drum flanges 24 and supported in substantially central position bymeans of the supporting members M. In such condition, the pistons 38 will be at rest at their upper limits of movement in their respective cylinders 49 and 48a at the front and rear wheels, and the plunger E5 in the master cylinder 58 will be disposed at substantially its upper limit of movement. When it is desired to apply the brake, the operator steps upon the pedal 82, forcing the plunger 75 downwardly until its lower end enters the reamed portion M of the cylinder body 69. As the plunger thus moves down, it closes the oil return port 93 and compresses the fluid disposed below it in the reamed portion M and in the chamber H8. The

pressure thus imposed upon the fluid in the system.

is transmitted equally in all directions, causing the pin valve 90a to move upwardly and close the oil supply from the engine and said fluid pressure is further transmitted through the conduits 6t and H12, and their respective branches iii, ltd and 532 to the several wheel cylinders. This results in downward or outward movement of the pistons 48, moving with them the brake-actuating levers 32 and 33. Assuming that the wheels are rotating at the time the foot pedal is depressed, expansion of the brake band 22 will continue until its lining 23 comes into frictional engagement with the inner periphery of the brake drum flange 2d, whereupon said brake band will tend to rotate with the brake drum. Such rotation, however, will be arrested by engagement of one end or the other of the brake band with the abutment 43, and accordingly, the two levers 32 and 33 will shift slightly in a lateral direction with reference to their pistons 48 so that the entire braking force will be applied through said levers to the other end of the brake band. The result is that the accumulated torque in each of the brakes is made use of in stopping rotation of the brake drums without having any adverse influence on the braking force applied by the actuating levers. With. this arrangement the wear on the brake band lining will be uniform throughout its entire area and such uniform wear also contributes to the increased life of the brake bands. As the operator subsequently releases the foot pedal, the fluid in the entire system tends to expand, with the result that the braking forces on the brake band are relieved and the several pistons return to their normal positions of rest, as previously described, and illustrated in the drawings. With the pistons properly fitted, the leakage of oil past them will be practically nil, by virtue of the connection of the master cylinder to the engine lubricating system, and it will be evident that even though there is a slight amount of leakage, the

braking system will be entirely filled at all times withbraking fluid, and therefore, there will be no lost motion of the pedal due to a reduction in the quantity of the luid. Furthermore, as has previously been pointed out, the oil return tube 9'! is disposed at substantially the highest point in the entire system and the result is that any air getting into the system will quickly work its way upwardly and be carried off through said tube El, thus eliminating lost motion from pocketed air. Another feature is that there are no piston rings or packing requiring frequent replacement, and all of the parts are so simple in construction as to be practically incapable of getting out of adjustment. The self-venting feature is really made possible by the disposition of the wheel cylinders at points substantially spaced below the wheel axes, while the master cylinder is disposed in a position above said axes, this relative arrangement making possible the gradual inclination of the oil conduits throughout their entire length. The extreme simplicity of the parts renders the entire braking system capable of manufacture at low cost, as compared with the prior art braking systems, and capable of application in vehicles wherein space for mounting the various parts is to a certain extent limited.

The several features of this invention may be used either with or without other features, and the invention is susceptible of numerous modifications in the details of construction and arrangement of parts. Therefore, the right is herein reserved to make changes as fall within the scope of the appended claims, wtihout departing from the spirit of the invention.

The present application is a re-filing of my application Serial Number 218,656, filed September 10, 1927.

Having thus described my invention, what I claim is:

1. In a vehicle having road wheels and brakes associated therewith and an engine for propelling the vehicle provided with an oiling system, a fluid pressure braking system including brake-actuating cylinders, means including pistons for transmitting power from said cylinders to their respective brakes, a fluid pressure creating unit,fiuid conducting means between said unit and the brake actuating cylinders, means for supplying oil to the pressure creating unit from the engine oiling system. of the vehicle and maintaining a circulation therein, and means for discontinuing the supply upon service application of the brakes. 2. In a motor vehicle, in combination, an axle, a steering knuckle, a bolt forming a pivotal connection between said steering knuckle and axle, a wheel rotatably mounted on said steering knuckle, a brake drum carried by said wheel, a brake band associated with said brake drum, a pressure cylinder carried by the lower end of said pivot bolt and coaxial therewith, a piston operably disposed in said pressure cylinder, and rocking elements interposed between the piston and the ends of the brake band, said rocking elements having free sliding engagement with the brake band and the piston.

3. In a motor vehicle, in combination, an axle, a steering knuckle, a bolt forming a pivotal connection between said steering knuckle and axle, a wheel rotatably mounted on said steering knuckle, a brake drum carried by said wheel, a brake band associated with said brake drum, a pressure cylinder integral with the lower end of said pivot bolt and coaxial therewith, a piston operably disposed within said pressure cylinder, rocking elements interposed between the piston and the ends of the brake band, said rocking elements having free sliding engagement with the brake band and the piston, and means for conducting pressure fluid to the pressure cylinder downwardly through the axle.

4. In a braking system for vehicles, brake members including self -energizing brake bands, a fluid pressure system, means for creating pressure in the system, and means responsive to the pressure therein to operate the brake members, each of said operating means including a pressure cylinder mounted in a fixed position, a piston slidable in said cylinder, a pair of levers interposed between the piston and opposing ends of the brake band, said levers having free sliding contact with the piston and the brake band, and floating pivotal means for said levers located intermediate the ends of the levers and oiTset therefrom.

5. In a braking system for vehicles, brake members including self-energizing brake bands, a fluid pressure system, means for creating pressure in the system, and means responsive to the pressure therein to operate the brake members, each of said operating means including a pressure cylinder mounted in fixed position, a piston slidable in said cylinder, 2. pair of levers interposed directly between the piston and opposing ends of the brake band and having sliding contact only with the piston and the brake band, and floating pivotal supports for the levers interposed between the ends of the levers, said levers having portions in rolling contact with each other and concentric with the pivots.

6. In a vehicle having a prime mover provided with a pressure lubricating system, a hydraulic brakin system including a master cylinder, oil supply line connections between the master cylinder and the pressure lubricating system for maintaining a full supply of liquid in the master cylinder, and a check valve to prevent transmission of braking pressure from the master cylinder to the lubricating system when the brakes are applied.

7. In a vehicle having a prime mover provided with a pressure lubricating system, a hydraulic braking system, and fluid conducting means for utilizing the pressure of the lubricating system to automatically circulate oil heatedby the prime mover for pressure transmission purposes from said pressure lubricating system to and through parts of said braking system when the brakes are in released position.

8. In a vehicle having a prime mover provided with a pressure lubricating system, a hydraulic braking system, fluid-conducting means for utilizing the pressure of the lubricating system to automatically circulate oil heated by the prime mover for pressure transmission purposes from said pressure lubricating system to and through parts of said braking system, and means to prevent return of the oil to the lubricating system when braking pressure is set up in the braking system.

9. In a vehicle having road wheels and brakes associated therewith, a fluid pressure braking system including brake-actuating cylinders, means for transmitting power from said cylinders to their respective brakes, a master cylinder, fluid-conducting means between the master cylinder and the brake-actuating cylinders, means for supplying oil to the master cylinder from the engine oiling system of the vehicle, and a heavier, non-freezing fluid in the brake-actuating cylinders and conducting means below the master cylinder, said heavier fluid being insoluble in the oil.

10. A fluid pressure braking system comprising foot-operated fluid pressure generating means, fluid pressure transmitting means, a non-freezing liquid in said transmission means, and a lighter insoluble liquid in the pressure generating means.

11. In a vehicle having a prime mover, a hydraulic braking system including a master cylinder for generating fluid pressure, and means for heating the fluid in said master cylinder including ducts communicating with the prime mover for permitting circulation of oil from the prime mover to the master cylinder.

12. In a vehicle having road wheels and brakes associated therewith and an engine for propelling the vehicle provided with an oiling system, a fluid pressure braking system including brake-actuating cylinders, means for transmitting power from said cylinders to their respective brakes, a unit for creating fluid pressure, fluid-conducting means between the unit and the brake-actuating cylinders, means for supplying oil to the unit from the engine oiling system of the vehicle, and means for discontinuing said oil supply upon creation of pressure by said unit.

13. A hydraulic brake comprising, in combination, a brake drum, a one-piece expansible resilient brake band fitted with a friction lining adapted to engage the drum throughout major portion of its circumferential extent, the brake band having limited floating movement with reference to the drum whereby to be self-energizing, an open-end pressure cylinder fixed with reference to the drum and adjacent to the ends of the brake band, a piston slidable in the cylinder, a pair of levers having sliding contact with the piston and the ends of the brake band, said levers having mutually-engaging portions in rolling contact with each other, and a pair of pivoted links giving floating support to said levers.

14. In a vehicle having a prime mover provided with a pressure lubricating system, a hydraulic braking system, and fluid-conducting means connecting the upper portion of said braking system with said lubricating system whereby to supply it with oil in constant amount, the lower portion of the braking system containing a heavier non-freezing fluid which is insoluble in the oil.

15. In a vehicle having a prime mover provided with a pressure lubricating system, a hydraulic braking system, a pressure creating unit in the hydraulic braking system, means for circulating the oil of the pressure lubricating system through the pressure creating unit, and means for interrupting the circulation of the oil through the pressure creating unit by operation of said pressure creating unit.

16. In a vehicle having a prime mover provided with a pressure lubricating system, a hydraulic braking system including brake actuating cylinders and a master cylinder, the master cylinder being located at a higher level than the brake actuating cylinders, with inclined fluid conducting means from the master cylinder to the brake actuating cylinders, means for circulating oil of the pressure lubricating system through the master cylinder for maintaining a constant level of oil in the master cylinder and permitting escape from the master cylinder of any air arising in the braking system, and means for interrupting circulation of oil from the pressure lubricating system through the master cylinder upon creation of pressure in the master cylinder for application of the brakes.

HUGH M. ROCKWELL. 

